1. Field of the Invention
The invention relates to a display device and a driving method. Particularly, the invention relates to a touch-sensing display device and a driving method thereof.
2. Description of Related Art
A display device having a touch-sensing function is generally implemented by a touch-sensing system and a display system independent to each other. System integration and lower cost are always unchangeable developing directions of the electronics industry. With progress of process technology, touch panels have been successfully integrated with display panels, and a user can directly control an electronic device to execute required tasks through touch-sensing. Generally, sensing units on the touch panel and pixel units on the display panel are all arranged in a matrix on a two dimensional plane, and frame update and timing for detecting a touch point are determined according to scan signals.
Generally, a difference of electrical properties of the touch panel before and after the touch-sensing operation has to be detected. Since the difference of the electrical properties is generally very tiny, prevention of noise interference is very important. However, when the display panel is driven, there are scan signals, data signals and common electrode signals, and when these signals are varied, the touch panel is interfered. With a development trend of integrating the touch panel and the display panel, interference therebetween becomes more severe. Some manufacturers manage to synchronize the signals of the display panel and the touch panel to avoid the interference. A method to avoid the signal interference is, for example, to add a synchronization signal between the display panel and the touch panel, so that a sensing time of the touch panel and a scan time of the display panel are not totally overlapped, or the synchronization signal is connected to a micro control unit (MCU) of the system, and the MCU controls a timing of the sensing operation of the touch panel, and reports corresponding touch coordinates. In other words, the above method uses the synchronization signal to notify an operation timing of the controller of the touch panel.